As 303EnfieldAU stated, the standard No.1 diagram will work just fine.
In addition to the caliber and steel differences, there are a few other minor differences...the extractor claw is longer and the bolthead is a bit different (no notch in back). The buttplate and it's screws are different and the butt has a higher comb to it. Also, it should have the late style nosecap (squared), and backsight protector (even on both sides). I believe the last two items are common with the late Ishy No.1Mk3's.